produced by Peter Firstbrook; contributors David Roberts and James Pitts.
Sun, cities and smog
This programme was filmed on location in Southern California, and in particular at the statewide Air Pollution Research Center in Riverside, which is pioneering research into exactly how photochemical smog is formed. One of the most recent discoveries is that smog may cause cancer at levels that were previously thought to be safe. But photochemical smog is not restricted to Los angeles; it can be found in any big city where there is a combination of sunshine and cars - New York, Sydney, Rome, Athens, Tokyo - even London has its problems in summer.
Sun, cities and smog